Recirculating Farms, Hydroponics and Aquaponics

What are the differences between recirculating farms, hydroponics and aquaponics? And what are their environmental benefits?

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Hydroponic and aquaponics farms are land-based systems that use recirculated, nutrient-rich water instead of soil to grow food, flowers and sometimes fish. 1 Hydroponic systems grow vegetables, herbs, some fruits and flowers in growth mediums such as coconut fibers or perlite. Aquaponics systems are hydroponic systems that include fish (the fish and plants are raised together in one system) which provide a source of fertilizer to the system and, depending on the species of fish, are harvested as a source of protein.

What Are Recirculating Farms?

Recirculating farms are closed-loop, land-based systems that use constantly-cleaned water to raise fish and grow food. There are three categories of recirculating farms: hydroponic, aquaponics and land-based fish farms.

Hydroponic Farms

Hydroponic systems grow plants in nutrient rich liquid, without what is traditionally thought of as soil (“dirt”). Nutrients are added to water. Plants may grow directly in the liquid, the liquid might periodically be sprayed on plant roots or it might flow across the roots as the liquid is recirculated in the system. Some farms use sand or gravel beds to support the plants as they grow.

Aquaponics Farms

Aquaponics farms are a combination of aquaculture and hydroponics — where fish are raised in tanks and the water from the fish tanks is recirculated into the plant beds, so the plants can absorb nutrients from fish waste in the water. When the water is returned from the plant beds to the fish tanks, it is cleaned of waste.

Hydroponic and aquaponics farming is not a new concept. Evidence of such systems dates to early civilizations, such as the Maya and Aztecs. 2 Fish are typically raised in outdoor ponds; but over that last four decades, the farming systems have been brought indoors, allowing for a more controlled environment. In the 1970s, researchers began adding plants to these systems as a means of cleaning the wastes produced by fish. A Berkley scientist brought hydroponics into the modern era with a commercial tomato system he established in California in the early 1900s. 3

Recirculating Fish Farms

Recirculating fish farms raise fish in tanks that have a water filter system to clean the water for constant reuse, just like an aquarium at home.

Types of Produce Grown in Recirculating Farms

Hydroponic and aquaponics farmers can grow many of the same things that are grown in traditional soil-based farms, including (but not limited to):

Herbs like basil, cilantro and mint

Vegetables like bell peppers, cucumbers and tomatoes

Greens like romaine lettuce, rainbow chard and spinach

Fruits like strawberries and melons

Flowers like cosmos, marigolds and zinnias

Aquaponics farmers can grow all the produce listed above plus they can raise many types of fish and shellfish in a separate tank, 45 including:

Edible fish and crustaceans like tilapia, catfish, trout and prawns

Ornamental fish like koi and goldfish

The Benefits of Hydroponic and Aquaponics Farms

Versatile and Flexible

Hydroponic and aquaponics systems are incredibly versatile 6 and, depending on the location and system design, can be affordable and space efficient. They are productive, produce little waste and require minimal inputs after the systems are established.

The systems don’t have to be complex; they can often be built with supplies from hardware stores and scaled up over time as space allows. Because they don’t follow a rigid design, they can be built inside or outside into odd-shaped or unusual spaces like backyards, basements or warehouses. The scale varies from small, personal use beds and tanks all the way through large, commercial-scale systems. They can be established in urban and rural spaces, where they can become a source of fresh, local food.

Land Efficient

Hydroponic systems can be stacked and grown vertically which means they don’t require large tracts of land. 7 Because they don’t require soil, they can be established in places where the soil is not suitable for farming.

Water Efficient

Once the initial water needs (which are variable and depend on the size of the system) are met, the amount of make-up water required is minimal, because water is circulated throughout the system and is reused. Some systems use as little as 10 to 15 percent of the water required by land-based farming. 8

Energy Efficient

The location and specific set up of a recirculating farm has a big impact on its energy needs; however, these systems can be efficient. Hydroponic systems established outdoors don’t require artificial lighting, and for those that are inside, energy needs can be minimized using efficient forms of lighting and solar energy. Aquaponics systems that match the type of fish to the region — for example, tropical fish in warmer regions — do not have the added expense of heating the water in cooler weather. 9

No Waste or Run-Off

Because the systems are, in effect, closed, there is little to no waste and no run-off generated. 10 Hydroponic systems require little to no pesticides or herbicides, and fertilizer use can be tailored to the system. Because the water is recirculated, there is no way for waste products to reach local waterways.

In aquaponics systems, no pesticides or herbicides are used because their use would kill the fish. Waste from the fish is used as a fertilizer for the plants. Solid waste that comes from the fish waste is often collected and used as compost.

Community Space

Systems that are established in urban areas can become gathering spaces for community members, especially in areas that lack such green spaces. Like community gardens, sites around the country are used as meeting places and offer educational and recreational spaces for activities like yoga classes and events.

Jobs and Job Training

Systems established in community spaces offer workers an opportunity to provide job training to volunteers. The plants, fish and facilities must be maintained, offering volunteers the opportunity to learn job skills. 11 In larger operations, there is enough labor required to create jobs. Because the systems can operate all year long, in some cases, year-round jobs rather than seasonal labor are created.

Community Resilience

Low resource requirements can make the systems easy to establish as a means of local food production that can help communities recover after disasters. 12 In addition, their designs make them less vulnerable to extreme weather conditions like heat, droughts and floods. For example, systems established indoors are not vulnerable to weather changes.

High Productivity

Hydroponic farming often outperforms soil-based farming in terms of the number of harvests of products per growing season 13 because when environmental conditions are controlled, year-round growth is possible. Some hydroponic systems have as many as 12 crop rotations per year. 14 This is also true for aquaponics in many cases. For example, some aquaponics systems can produce market-sized fish in just nine months. 15 In addition, farmers can switch crops as necessary to meet demand — even out-of-season demand.

Local Access to Produce and Fish

Because hydroponic and aquaponics systems can be established anywhere — from tight urban spaces to remote rural places — once they are established, they can be a source of local produce and/or fish that can help reduce food insecurity. 16

Systems that are established at a scale larger than personal use can provide local sources of fish and produce to the community. The goods can be sold directly to consumers on site or at farmers’ markets, or can be delivered through CSAs. 17

No Habitat Destruction

Hydroponic and aquaponics systems can be established almost anywhere and in any configuration — from tropical climates to arid deserts to temperate regions, indoors or outdoors, in many shapes and designs. There is no need to alter natural habitat to establish food production. 18 This helps to preserve sensitive habitats like coastal regions or arid grasslands.

Potential Pitfalls with Hydroponic and Aquaponics Farms

Electrical Use

Depending on how and where they are established, hydroponic and aquaponics systems can have high energy costs. This is because they incorporate lighting, pumping, air moderation and — where fish are included — possibly water heating. 19

Energy costs associated with lighting used to be a significant part of hydroponic operating budgets but with advancements in efficient LED lighting, those costs have come down. The true costs of set up and operation will be determined by scale, location and whether the system is set up outdoors where it can take advantage of sunlight, or indoors where artificial lighting and air movement will be required. 20

For aquaponics systems established where the climate is not suited to the type of fish being grown — for example, growing tropical fish like tilapia in colder climates — water heating might be required, which could significantly increase energy costs. 21 Additional energy requirements include water circulation via pumps.

Initial and Make-Up Water Requirements

Water requirements for hydroponics and aquaponics systems are generally low compared to land farming. 22 Meeting the initial water requirements is generally not an issue, unless the system is located in a water-stressed environment or there is not a ready source of water; for example, a system located in an empty city lot where there is no plumbing infrastructure in place and water must be obtained from offsite sources like fire hydrants. Once the initial water supply is in place, make-up water needs are generally minimal and can often be filled by rainwater. 23

Fish Feed

Depending on the type of fish raised in aquaponics farms, feed can present a challenge. Fish that are carnivorous are often given feed made up in part by small, wild fish taken from the sea, like menhaden. 24 These fish are a primary food source for marine wildlife — dolphins, birds and larger fish — and are also critical to the diets of many coastal communities worldwide. 25 Many aquaponics farmers raise fish (like tilapia) that can be fed a vegetarian diet; however, this type of feed often includes grains like soy and wheat and other commodity crops that are dependent on industrial farming practices. 26 Many farmers find other, more sustainable sources of feed for their fish, such as duckweed or black fly larvae.

Start-Up Costs

Compared to traditional farming, hydroponic and aquaponics systems potentially have low start-up costs, primarily because large amounts of land are not required. 27 Depending on the scale, system design and location, the initial and operating costs could be significant.

Initial costs include the cost of acquiring land/buildings or rent on those spaces, equipment like tanks, pumps, tubing/hoses and plant rafts, energy for lighting and heating, water (if a ready source does not exist, as might be the case in a rural location or in an abandoned urban lot), materials, plant starters, fish frying and building supplies.

On-going costs include labor, energy usage and fish feed for aquaponics. When all costs are considered, the bulk of the costs come from energy use and labor, and (depending on the set up), potentially, rent. 28

Some enterprising companies are preassembling hydroponic kits in cargo containers and selling everything required to start a hydroponic farm just about anywhere, for a set price. 29 The set up could be more challenging with the jump to aquaponics, as the addition of fish brings additional requirements for heating, fish feed and additional space.

Selling Fish and Produce Profitably

Both hydroponic and aquaponics farms are receiving a lot of attention in the media which is helping to build their success. There is growing interest from venture capitalists to establish large-scale systems, primarily in hydroponics. Guides that explain typical start-up costs indicate that hydroponic farms can become profitable quickly depending on the set up. 30 Aquaponics systems that have strong educational components and are run as non-profits tend to do better than commercial aquaponics ventures. 31 There are fewer commercially successful aquaponics farms than there are hydroponic farms around the country.

Some studies have compared the profitability of aquaponics farms to that of small land-based farms and found they tend to be similar in size and gross sales revenue. They also found, similarly, that aquaponics farmers often must take off-farm work, to earn a viable income. 32 This is true for many small farmers in that much of their household income stems from off-farm activities. 33

Research suggests that, like other small farms, aquaponics farms tend to be more profitable if farms diversify their revenue stream, for example, by selling non-food products and aquaponics-related services, or conducting educational trainings. 34 The EPA has produced a start-up guide to help potential aquaponics farmers create a viable business plan. 35

Finding Aquaponically-Raised Fish to Eat

Hydroponic crop farming in the US is a growing industry generating $848 million in revenue between 2012 and 2017 and growing at a rate of four percent annually. 36 While hydroponic farms are increasing and finding hydroponically grown produce at the supermarket is becoming commonplace, fish cultivated through aquaponics are more difficult to find. No listing of aquaponics farms is yet available to draw from, so learning about their products may require research. However, this could change as the number of farms increases.

Organic Certification

While some hydroponic and aquaponics producers have received organic certification, there has been a debate over whether those certifications were justified and whether growing crops in water falls under organic certification. At issue 37 is whether organic growing methods necessarily must include roots growing in soil, or whether they can also include roots grown in water and growth media with organic fertilizers. Many organic soil farmers maintain that the core of organics is about healthy soil, therefore, food grown in water should be excluded. 38 Nevertheless, the National Organic Standards Board recently voted not to exclude hydroponic and aquaponics farms from organic certification. 39

Investments in Recirculating Farms

Hydroponic and aquaponics growing systems have a lot of benefits that make them attractive to venture capitalists. Recent multimillion dollar investments in NYC-based BrightFarms, Gotham Greens and Edenworks indicate that investors are supportive of the technology and are willing to provide financial backing. Because of this, the systems are getting a lot of media attention, which is a plus for those looking to start a hydroponic or aquaponics farm in their location.

What You Can Do

Learn more about hydroponics, aquaponics and recirculating fish farms.